At present, mobile phones have been greatly involved in daily life of people. As one of the most important interfaces of a mobile phone, a Universal Serial Bus (USB) interface is the most basic device in each mobile phone. Designs of mobile phones tend to be large, thin and light, and under such a tendency, conventional USB interfaces will certainly be eliminated and replaced with more compact mini-USB interfaces and micro-USB interfaces. Micro-USB interfaces are the most common USB interfaces on the current market.
Since wireless charging has not yet been popularized in a large scale, most of mobile phones can only support USB interface charging. The inventor discovers in a research process that it is difficult for a user to accurately plug a charger into a USB female interface on a mobile phone in a dark place under the condition that the micro-USB charger is flat and narrow, one reason is that USB interfaces have a difference in positive and negative directions and directions of male and female interfaces are required to be consistent, and another reason is that a position of the female interface in the mobile phone cannot be accurately found. Although a screen of a mobile phone can emit light, a direction of the light is perpendicular to a direction of a USB interface, and under the interference of the light, a lateral surface where the USB interface is located becomes a blind area.
Under such a condition, the user has to try to look for the position with double hands, and has to look for the position again if the directions of the USB male and female interfaces are inconsistent; or the user has to find the position to finish charging by virtue of another light source, which brings inconvenience.
For the problem of difficulty in accurately finding a position of a USB interface on a device in a dark environment in a related technology, there is yet no effective solution.